Non-fluid stimulation of porous media

Abstract

Resonant sweeping frequencies are estimated for specific rock types, saturated with various formation fluids at reservoir conditions. A sequence and duration of resonant frequency sweeps and high amplitude low frequency vibration / agitation at each station is designed based on petrophysical and geomechanical properties, and in-situ stress conditions. Resonant sweeping and agitation is conducted as a multiple resonant frequency (fixed or variable) tool passes at optimal speed, which will be determined for specific reservoir type and downhole conditions. Resonant stimulation tool type, or combination of tools, is selected based on borehole size, reservoir parameters and resonant frequency requirements to maximize the efficiency of stimulation. Broad range of operating frequencies will allow to tune to resonant frequencies of various formation types (sandstones, limestones, shales, dolomites, and heterogeneous reservoirs comprised of the mixture of above lithologies). Low frequency transducers increase fluid displacement, and improve ultimate formation fluid recovery.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of priority of U.S. Provisional Application No. 63 / 058,940 filed Jul. 30, 2020, which is incorporated herein by reference.BACKGROUND OF THE INVENTION(1) Field of the Invention[0002]The invention pertains generally to reservoir stimulation in the oil and gas industry, geothermal and agricultural industry, disposal industry and mining sector. More specifically, the invention relates to a process methodology and associated downhole apparatuses for non-fluid stimulation of porous media (reservoir stimulation).(2) Description of the Related Art[0003]The current mainstream approach for reservoir stimulation is hydraulic fracturing. These high-pressure stimulations require the injection of fluids and slurries typically composed of water, sand, hydrocarbons, solvents, or chemical solutions.[0004]Drawbacks of hydraulic fracturing include induced regional seismicity, water resource limitations, cost and transport...

AI Technical Summary

Benefits of technology

The invention is a process for non-fluid stimulation of reservoirs, such as oil and gas, using acoustic waves and high amplitude low frequency vibrations to increase the permeability of the reservoir and reduce viscosity of produced hydrocarbons to improve inflow and reservoir performance. The process creates a high-density network of interconnected microfractures, which results in fatigue failure and cohesive strength failure of the reservoir, leading to increased permeability. The low frequency vibration releases trapped fluids as the result of poroelastic motion. Reservoir heating at optimum temperatures will vaporize bound fluids and partially remove hydroxyl / structural water in the clay lattice, creating additional cracks / microfractures and enhancing reservoir permeability. The patent is also about a double wall heating tubing design that allows for simultaneous hydrocarbon production and energy consumption. The process can be applied in oil and gas, geothermal, agricultural, and downhole disposal applications.

Problems solved by technology

Drawbacks of hydraulic fracturing include induced regional seismicity, water resource limitations, cost and transportation of high volumes of water and proppant, well integrity / cement damage, large well surface site pads, and political sensitivity (anti-fracing campaigns).

This means the reservoir may not be evenly stimulated—stranding resource and reducing ultimate recoveries.

Furthermore, as reservoirs deplete, many follow-up wells (child wells) show much reduced results than original (parent) wells when hydraulic fractured.

In essence, child wells may exhibit ‘frac hits’ to other wells, causing inter-well communication and lack of reservoir stimulation.

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